Feeding Frenzy

After an unhealthy hot sandwich in the office this morning, I decided to take a walk up to Greenhead Park at lunchtime. The snow was starting to melt but there was still enough around for people to be sledging and making rude snow sculptures variations to the usual snowmen.

The lake was partially frozen with a layer of water on top of the sheet ice. 

The resident ducks didn't stand much of a chance against these gulls at feeding time.

I am hopeless at identifying gulls. Any suggestions?